The overall aim of this project is to investigate the factors associated with men becoming unwed fathers and the nature and consequences of unmarried fathers'involvement with children. This is an important topic, given the large and growing number of men who will have at least one child outside of marriage and the large fraction of children and mothers who will be exposed to their fathering behavior. Yet, our knowledge about nonmarital fathering and how it affects partners, children, and the fathers themselves remains limited, in part because men are often under-represented in national surveys. Fathers represent an important resource for children, ideally investing the time, money and emotion that promote healthy child development and socialization, but unwed fathers often have individual and contextual characteristics that deter and complicate their potential for positive involvement in family life;these include low human capital, high rates of social-behavioral problems, and a high likelihood of living away from their child, as well as three important but little explored factors related to nonmarital fathering fathers'ongoing relationships with mothers (whether romantic and/or co-parenting), the fact that unmarried men (and women) often have children by multiple partners (so-called `multi-partnered fertility'), and the fact that a non-trivial number of unwed fathers have been or will be incarcerated. Using three national datasets (the National Survey of Family Growth, the National Longitudinal Survey of Youth 1979, and the Fragile Families and Child Wellbeing Study), this research will provide new information about the trajectories and consequences of recent and contemporary nonmarital fathering. The study includes three specific aims: 1) To evaluate the antecedents of nonmarital fatherhood and the effects of becoming an unwed father on the male life course;2) To analyze the nature and dynamics of unwed fathers'involvement in families as partners and parents, especially as linked to relationships with mothers, multi-partnered fertility, and paternal incarceration;and 3) To examine the consequences of unmarried fathers'involvement for the wellbeing of children and of fathers themselves, including whether the benefits are moderated by fathers'characteristics or context. Using a life course perspective and drawing on family systems theory, this project will evaluate key stages and turning points in men becoming and then being unmarried fathers, including factors that both enhance and deter positive parenting over time. The study will explore race/ethnic differences in unwed fathering and consider key analytic challenges related to social selection and missing data. Overall, this study will provide new information about the process, content, and consequences of nonmarital fathering for children and families and may shed light on the development of sound policies and programs to strengthen families. PUBLIC HELATH RELEVANCE This study will provide new information about the factors associated with men becoming unwed fathers and the nature and consequences of unmarried fathers'involvement with children. Given the rising fraction of births that occur outside of marriage and the negative consequences of father absence for children, this study will provide information to aid the development of sound policies and programs to keep fathers connected to children and to strengthen families across diverse contexts.